Roller converor tracks are often used for example in freight loading systems in air freight traffic for conveying freight containers or other articles within the interior of the freight compartment of freight aircraft. Typically, a roller conveyor track which may be used in that situation comprises a plurality of rollers which are free-running and/or driven by an electric motor, disposed in succession at a spacing from each other in the direction of conveying movement, with their axes of rotation transverse relative to the direction of conveying movement. At least the free-running rollers are releasably mounted by means of shaft portions at the ends thereof, in openings provided in vertical side walls of an upwardly open channel configuration in a supporting structure. The supporting structure may comprise a plurality of upwardly open, U-shaped metal members which are anchored in mutually parallel relationship in the direction of conveying movement, to the bottom of the freight compartment. Provided in the side walls of the metal members and arranged in pairs in oppositely disposed relationship are rows of bores or holes in which the shaft portions on the conveyor rollers are suitably fixed.
One possible form of the arrangement for fixing and mounting the conveyor rollers in such a roller conveyor track is to be found in German patent specification No. 3 210 204. As the two side walls of the U-shaped members are fixed at a spacing relative to each other, that arrangement provides that the shaft portions which project away from the two axial ends of each roller are arranged to be such that they can be pushed axially into the roller so that the roller can be fitted into the U-shaped member by retracting the shaft portions in that way, with the two shaft portions then being fixed in the respective holes for receiving same. Fixing of the respective rollers is effected by a procedure which provides that, after the shaft portions have been pushed in, the roller is firstly fitted into position between the two side walls of the U-shaped member, and then a screw bolt is inserted from the outside of the side wall, through the bore, and screwed into an axial screwthread in the corresponding shaft portion of the roller so that the shaft portion is drawn into the opening in the side wall of the U-shaped member, and fixed in position therein.
A construction of that kind has a large number of mechanically movable components which are also of a really complicated configuration so that in general terms, besides a high level of manufacturing costs, that arrangement is also of a substantial weight which is a highly undesirable consideration, precisely in relation to use in an air freight system. In addition it is also essential that the outer side walls of the U-shaped members are kept freely accessible so that the rollers can be fitted or replaced by screwing the screw bolts in or releasing them, from the outside.
The need for the outside walls of the U-shaped members to be kept freely accessible thus means that the roller conveyor track is of a design configuration in which the individual U-shaped members project upwardly from the floor of the freight compartment, which in itself is a flat floor, thus resulting in a floor surface which is so-to-speak cluttered up with impediments and obstacles, in the form of the U-shaped members. In addition, there is always the risk of damage to the individual roller tracks as they project upwardly from the floor of the freight compartment in a free-standing and thus essentially unprotected fashion.
Entirely similar problems also arise in relation to drive roller units of such a roller conveyor track, which are provided at various points in the roller tracks, for driving the freight containers and the like which are to be conveyed thereon.